We chose to use ARP 2000 material head studs on the X3 as it only uses a M9 stud compared to most others MFG M10. On all other UTV's we use 8740 studs as the ARP 2000 is not needed in the M10 and M12 other manufactures use. This material is 4 times the cost of the standard ARP 8740 chromoly head stud and offers much more strength. We feel that with the small M9 studs it is needed.